The present invention relates to a method for manufacturing a drill blank or a mill blank by extrusion comprising the forming of a first blank portion having external, helical chip flutes and the forming of a further blank portion in the shape of a shaft. The invention also relates to a device for manufacturing a drill blank or a mill blank. The drill blank or the mill blank is further treated in subsequent manufacturing steps to obtain a drill for chip removing machining.
U.S. Pat. No. 4,779,440 discloses a method for producing extruded drill blanks. The extruded drill blanks are equipped with external, helical grooves that serve as the beginnings for the subsequent chip spaces of the drill. Preferably, the chip spaces are produced by grinding. The drill blanks are obtained by extruding a heated hard metal material through a nozzle. The drill blanks can be joined to a handle in a manner known per se.
WO 00/74870 discloses a method for manufacturing a rotary tool such as a helix drill or an end mill for example, the method comprising the forming of a blank by an extrusion process. During the extrusion, a mixture is passed through a die which provides a cylindrical shape to the outer peripheral surface of the mixture. A plurality of jaws are disposed downstream of the die for conducting the mixture. Each jaw includes a helical ridge for engaging the outer surface of the extruded mass to cause a helical groove to be formed therein which constitutes a chip flute in the tool. During the extrusion, the jaws are moved away from the mixture to terminate formation of the chip grooves, whereby a shank portion of the tool is formed.